Pork bellies are injected with a curing solution, called pickle, in order to make bacon. Conventional injection machines have a vertically reciprocating crosshead with multiple needles. The crosshead is typically driven by a crank. A normal conveyor carries the bellies under the needles and is moved intermittently ahead when the needles are removed so that a pattern of intermittent injections are made in the bellies as they incrementally move under the needles, and are then injected as they become stationary between intervening movements.
The needles project down through to the bottom of the belly as the belly lays on the stationary conveyor and then the needles stop and reverse direction and return upward out of the bellies. The needles and crosshead continue their upward stroke above the bellies while the conveyor moves forward to place the belly for another injection. Also, as the needles clear the top of the bellies, the stripper plate that held the bellies in place is raised by the crosshead to allow movement of the belly under the needles.
The pump for the pickle is usually a positive displacement pump and pumps pickle through the needles at a constant rate. When the needles are out of the bellies, the pickle is usually allowed to continue to run from the needles and is collected underneath the bellies and re-filtered and fed back into the reservoir to be used again.
Such fluid injection machines for meat products have been used for many years, but they have several negative factors, one of which is very detrimental. The distribution of pickle throughout the belly should be as uniform as possible. That means that every cubic centimeter should have the same amount of pickle throughout the entire belly. When the crosshead and needles are moved up and down by a crank mechanism, the velocity of the needles is constantly changing from zero to maximum and back to zero, etc. as the needles move up and down in the belly. With a constant flow pump, the bellies get more or less pickle per cubic centimeter, depending on the velocity of the needles in moving into and out of the meat.
Stated differently pickle is generally supplied into the injector head by a positive displacement pump with constant flow rate. The needles driven by a rotational crank travel at a variable speed through the thickness. When needles are near either top or bottom position, the needle traveling speed is close to zero, while at the middle-stroke needles travel at the highest speed. More pickle is injected per unit length of travel when needles are moving at slow speed and less pickle is injected at high speed. It is highly desirable to inject equal amount of pickle per unit length of thickness to achieve the best quality of injection.
Another negative feature of past injection machines is the bad inertial forces that build up in the conveyor as it starts and stops. The conveyor with its load of bellies must be stopped when the needles are injecting pickle into the belly. When the needles are out of the belly, the conveyor must move ahead to place the belly in position for another injection by the needles. This arrangement necessitates continual starting and stopping of the conveyor with its heavy load of bellies, and this is very undesirable. Since the injector head moves in a nearly vertical direction, the conveyor has to stop during the injection process to allow needles to penetrate into and out of pork bellies without introducing the lateral motion. This intermittent motion of the conveyor accelerates and decelerates pork bellies and creates inertia forces to shake the whole injector machine.
The noise level generated from injection operation will be greatly reduced if the conveyor has a continuous motion.
Another problem with past injectors is the flow of pickle when the needles are out of the bellies. Some injectors allow the pickle to continue to run out of needles where it is collected and returned to the reservoir. Other injectors start the flow after the needles start into the bellies and shut off the flow as the needles are coming out of the bellies. This starting and stopping of the flow is an inertial problem. Also, letting the pickle flow continuously and catching it and returning it to the reservoir is undesirable.
Therefore, it is a principal object of this invention to inject meat products with a fluid as the meat moves continuously through a fluid injection station without having to stop the meat product while it is being injected.
A further object of the invention is to inject a meat product with a battery of needles by pumping the fluid constantly, with fluid going into the injecting needles while they are in the meat product, and with the fluid bypassing the needles and returning to the fluid reservoir when the needles are out of the product.
A further object of this invention is to create a uniform pickle injection through the thickness of pork bellies by using a double action piston pump with its output flow rate matching the velocity of the injecting needles.
A further object of this invention is to eliminate the inertia load created by the intermittent motion of the conveyor and pork bellies placed on the conveyor by using a continuously moving conveyor to carry pork bellies.
A further object of this invention is to develop a driving mechanism so that the lateral motion of the injector head during the injecting process matches the linear speed of the conveyor and the injector head is returned back to its beginning position for next cycle while needles are out of pork bellies.
A further object of this invention is to control the pickle flow into the injecting needles only during the injecting process and to direct the pickle flow back into reservoir without starting or stopping the piston pump and pickle flow.
A further object of this invention is to adjust the output flow rate of the piston pump to achieve desired percentage of pickle injection.